JPH02135114A - Production of oxygen enriched air - Google Patents

Abstract

PURPOSE:To economically produce oxygen enriched air by separating air into cold air and hot air, passing the cold air through an adsorbent to adsorb oxygen and passing preheated air through the adsorbent to desorb the oxygen. CONSTITUTION:Each of columns 1A-1C is packed with activated carbon granules as an adsorbent. Air compressed by a compressor 3 is introduced into a vortex tube 2 and separated into cold air 2a and hot air 2b. The cold air 2a is introduced into the column 1A to adsorb oxygen on the adsorbent. Waste gas produced by combustion in a boiler 5 is exhausted from a chimney 6 through a heat exchanger 4 and the sensible heat of the waste gas is used to heat air sent through a blower 8. This preheated air is introduced into the column 1B to desorb oxygen adsorbed in the preceding stage and the resulting preheated oxygen enriched air is efficiently used in the burner 7 of the boiler 5. The cold air passed through the column 1A is introduced into the column 1C heated in the preceding stage to regenerate the adsorbent to such a degree that the adsorbent can adsorb oxygen in the subsequent stage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing oxygen-enriched air for combustion with a low content of nitrogen gas and moisture.

[Prior art] Not only does the nitrogen and moisture contained in the combustion air not undergo a combustion reaction, but the nitrogen and moisture also require heat when heated to the required temperature, so extra fuel is used. Not economical. For this reason, methods have been proposed to reduce nitrogen and moisture in the air and produce combustion air enriched with oxygen.

For example, as shown in Japanese Unexamined Patent Publication No. 51-67283, a pressure swing method in which a zeolite molecular sieve is pressurized to adsorb nitrogen, enrich the oxygen concentration in the air, and then depressurized to separate and regenerate nitrogen; As shown in Publication No. 54-62994, the adsorbent is separated into two or more parts and stored, with one part producing oxygen-enriched air and the other producing high-temperature exhaust gas discharged from the combustion equipment. There is a temperature swing method in which heat-exchanged air is sent in.

[Problems to be Solved by the Invention] However, conventionally proposed methods require a large amount of power or heat, making oxygen enrichment expensive. Recently, an efficient pressure swing method has been proposed by improving adsorbents, but the power energy required for compression is not small.

On the other hand, in the temperature swing method, the nitrogen adsorption capacity of the adsorbent decreases dramatically in the high temperature range of 50°C or higher, so a temperature swing using high temperature exhaust gas requires a large amount of adsorbent, increasing equipment costs. It wasn't very economical.

The present invention provides an economical oxygen-enriching manufacturing method.

[Means for Solving the Problems] The gist of the present invention is a method for producing oxygen-enriched air that enriches oxygen in the air using an adsorbent, which includes separating air into low-temperature air and high-temperature air, A method for producing oxygen-enriched air, which comprises passing separated low-temperature air through an adsorbent to adsorb oxygen, and passing preheated air through the adsorbent to dissociate oxygen to obtain oxygen-enriched air. It is.

When low-temperature air is passed through, for example, an activated carbon molecular sieve as an adsorbent, oxygen in the air is absorbed, and conversely, when high-temperature air is passed through, the oxygen absorbed by the adsorbent is released. Based on this principle, the present invention is capable of: ■ Adsorption of oxygen in combustion air; ■ Preheating of combustion air by sensible heat of exhaust gas and dissociation of oxygen from the adsorbent; ■ Preheating of combustion air and cooling of adsorbent. Each process is performed efficiently by combining a plurality of adsorbent-filled cylinders and switching them alternately, making it possible to enrich oxygen through continuous adsorption. In particular, this method differs from conventional methods in that the amount of oxygen adsorbed by the adsorbent is greatly increased by using cold air, and in that the cooling effect in the regeneration process is improved by using low-temperature gas.

The means for separating raw air into low-temperature air and high-temperature air is 19
It is preferable to use the Portex tube introduced by the French physicist Portex in 1931.The Portex tube is a circular tube with an orifice at one end and a doughnut-shaped gap at the other end, as shown in Figure 2 (A). When compressed air 2c is blown into the circumferential direction, a super high-speed vortex is created inside the tube. This creates a large pressure difference between the center and the outer periphery of the vortex, causing air to move toward the center, causing the temperature to drop due to expansion. Cold air 2a generated at the center flows out from the orifice, and hot air 2b at the outer periphery is released from the donut-shaped gap.

In other words, it is possible to easily produce cold air and hot air using a portex tube, which is a simple structure.

[Example] The present invention will be described in detail below using embodiment examples shown in the drawings.

This example was carried out to enrich the combustion air of the boiler 5 with oxygen, and FIG. 1 shows the overall configuration of the apparatus used in this example, with lines IA and IB.

The IC is an adsorbent-filled cylinder, and activated carbon molecular sieve, which improves oxygen adsorption ability, is molded into a particle size of 3 aun and loaded into each cylinder as an adsorbent.

The air that has now been compressed to 3 kg/cm'' by the compressor 3 is separated by the portex tube 2 into 10°C cold air 2a and 110°C hot air 2b at a ratio of 9:1, and this cold air 2a is adsorbed. The agent is introduced into the cylinder IA, and the oxygen and elements are first adsorbed on the activated carbon molecular sieve. Next, the exhaust gas generated by combustion in the boiler 5 passes through the heat exchanger 4 and is discharged from the chimney 6, and the sensible heat of the exhaust gas is transferred to the blower. The hot air 2b from the portex tube 2 is used to heat the air pumped from the portex tube 2 to 150°C.
The preheated air may be mixed with exhaust gas to produce preheated air. This preheated air is introduced into the adsorbent packed cylinder IB to dissociate the oxygen adsorbed in the previous step and produce preheated oxygen-enriched air. It can be efficiently used as the burner 7 of the boiler 5. The adsorbent filled cylinder IC heated in the previous step is cooled by introducing cold air passed through the filled cylinder IA and regenerated to enable adsorption in the next step. This completed one cycle, and by repeating this operation alternately, it was possible to continuously produce preheated oxygen air. This iterative process is shown in Table 1.

The cycle of steps shown in FIG. 1 and Table 1 was carried out at 15 minute intervals with fully automatic switching, and it was possible to continuously and stably enrich the combustion air with oxygen valves from 21% to about 25%.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various design changes can be made as long as the requirements of the present invention are met. Since high-pressure gas is not required in each process, it is also possible to continuously produce oxygen-enriched air using a rotary system.

Furthermore, in order to produce cold air and hot air, in addition to using the portex tube 2 described above, it is also possible to adopt a heat exchange method as shown in FIG. 2(B). It uses a refrigerator that circulates fluorocarbon gas through a compressor 9, and a part of the raw air is cooled by a heat exchanger 10a.
It is also possible to produce heated air by discharging the sensible heat to the remainder of the raw air using the heat exchanger 10b. Furthermore, it is also possible to simply use an expansion valve 11 as shown in FIG. 2(C).

[Effects of the Invention] As explained above, according to the present invention, oxygen enrichment in combustion air can be efficiently and continuously increased using sensible heat of exhaust gas, contributing to energy saving.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the overall configuration of the device used in the example, Figure 2
Figures (A), (B), and (C) are explanatory diagrams relating to methods of producing cold air and hot air, respectively, from raw air. IA, IB, IC...Adsorbent filling cylinder 2...Portex tube 3...Compressor 4...Heat exchanger 5...Boiler 7...Burner 9...Compressor 10a, 10b. ... Heat exchanger 11 ... Expansion bow length valve. 6...Chimney 8...Blower Figure 1

Claims (1)

[Claims] 1. A method for producing oxygen-enriched air that enriches oxygen in the air using an adsorbent, in which air is separated into low-temperature air and high-temperature air, and the separated low-temperature air is adsorbed. A method for producing oxygen-enriched air, which comprises passing preheated air through an adsorbent to adsorb oxygen, and dissociating oxygen by passing preheated air through the adsorbent to obtain oxygen-enriched air.